Wearable exoskeletons have been designed for medical, commercial, and military applications. Medical exoskeletons are often used to restore and rehabilitate proper muscle function for people with disorders that affect muscle control. Medical exoskeletons include a system of motorized braces that can apply forces to a user's appendages. In a rehabilitation setting, medical exoskeletons are controlled by a physical therapist who uses one of a plurality of possible input means to command an exoskeleton control system. In turn, the exoskeleton control system actuates the position of the motorized braces, resulting in the application of force to, and typically movement of, the body of the user. Medical exoskeletons can also be used outside of a therapeutic setting to grant improved mobility to a disabled individual. Commercial and military exoskeletons are used to alleviate loads supported by workers or soldiers during their labor or other activities, thereby preventing injuries and increasing the user's stamina and strength. Tool-holding exoskeletons are outfitted with a tool-holding arm that supports the weight of a tool, reducing user fatigue by providing tool-holding assistance. The tool-holding arm transfers the vertical force required to hold the tool through the arms of the exoskeleton rather than through the user's arms and body. Similarly, weight-bearing exoskeletons transfer the weight of an exoskeleton load through the legs of the exoskeleton rather than through the user's legs. In some cases, weight-bearing exoskeletons are designed to carry a specific load, such as a heavy backpack. In other cases, military weight-bearing exoskeletons support the weight of armor. Commercial and military exoskeletons can have actuated joints that augment the strength of the exoskeleton user, with these actuated joints being controlled by the exoskeleton control system, and with the exoskeleton user using any of a plurality of possible input means to command an exoskeleton control system.
In powered exoskeletons, exoskeleton control systems prescribe and control trajectories in the joints of the exoskeleton, resulting in the movement of the exoskeleton. These control trajectories can be prescribed as position-based, force-based, or a combination of both methodologies, such as those seen in impedance controllers. Position-based control systems can be modified directly through modification of the prescribed positions. Force-based control systems can also be modified directly through modification of the prescribed force profiles. Complicated exoskeleton movements, such as walking in an ambulatory medical exoskeleton, are commanded by an exoskeleton control system through the use of a series of exoskeleton trajectories, with increasingly complicated exoskeleton movements requiring an increasingly complicated series of exoskeleton trajectories. These series of trajectories can be cyclic, such as the exoskeleton taking a series of steps with each leg, or they can be discrete, such as an exoskeleton rising from a seated position into a standing position. In the case of an ambulatory exoskeleton, during a rehabilitation session and/or over the course of rehabilitation, it is highly beneficial for the physical therapist to have the ability to modify the prescribed positions and/or the prescribed force profiles depending on the particular physiology or rehabilitation stage of a patient. As different exoskeleton users may be differently proportioned, variously adjusted or customized powered exoskeletons will fit each user somewhat differently, requiring that the exoskeleton control system take into account these differences in exoskeleton user proportion, exoskeleton configuration/customization, and exoskeleton user fit, resulting in changes to prescribed exoskeleton trajectories.
While exoskeleton control systems assign trajectories to the joints of the exoskeleton and control the positions of these joints, the actual forces applied to exoskeleton joints are exerted by actuators. These actuators can take many forms, as is known in the art, each with advantages and disadvantages in various applications. In current exoskeletons, the actuator exerting force on a joint typically comprises an electric motor located proximal to the joint that is being controlled. Exoskeletons also are equipped with a variety of sensors, as is known in the art, with these sensors reporting information on exoskeleton state to the exoskeleton control system.
Ambulatory exoskeleton-based physical therapy is currently in use with patients that have been affected by a variety of conditions, including stroke and spinal cord injuries. Such patients may have reduced or no ability to control certain muscles, including muscles involved in walking. These same patients, in many cases, also use wheelchairs for purposes of mobility. Wheelchairs, including both powered and manual wheelchairs, are a very efficient form of transportation in certain environments—though many natural and man-made environments are inaccessible to wheelchairs. Dynamic wheeled mobility is exemplified in the marketplace by specialized standing and/or tilt/recline wheelchairs (both manual and powered), as well as the recently developed and commercialized “Elevation” wheelchair. In addition, the device described in International Application No. PCT/CA2013/050836, which is incorporated herein by reference, allows an exoskeleton and user to sit in a specific wheeled base, with this wheeled base being compatible with the exoskeleton frame. The wheeled base includes mechanisms to assist the exoskeleton and user in standing while doffing the wheeled base or in sitting while donning the wheeled base. The wheeled base aims to overcome disadvantages seen in some current exoskeletons, such as slow exoskeleton gait and limited exoskeleton range, as well as relatively complex exoskeleton operation compared to that of a wheelchair, by allowing the exoskeleton user to use the wheeled base like a wheelchair in situations or environments where the use of a wheelchair would be preferred to an exoskeleton.
One disadvantage of combining an exoskeleton with an unpowered wheelchair is the extra weight the user has to maneuver during rolling actions and while entering and exiting automobiles. Minimizing loading on the user's shoulders and other body parts is important in preventing repetitive stress injuries and fatigue. The ability of the wheeled base to provide rolling assistance is not novel as there are many powered wheelchairs already invented, but powered wheel propulsion is one way to overcome the burden upon a patient of maneuvering the extra weight of the exoskeleton when combined with a wheeled base. A major benefit of integrating a wheeled base and exoskeleton is the energy efficiency of rolling transport compared to walking. An exoskeleton will weigh a minimum of 20 pounds, and could be as heavy as 70 pounds, so supporting the exoskeleton weight on a wheeled base will make moving it from one location to another easier than other methods, such as taking the exoskeleton apart and putting it into a bag or case. Another benefit of transporting an exoskeleton on a wheeled base is that the weight can be balanced ideally between the front and rear wheels since it is aligned with the user's body (this is how wheelchairs are configured for stability). Transporting an exoskeleton in a bag or case could require it to be carried in the user's lap or supported on the front or back of the wheelchair, thus requiring additional wheels or counterweight to prevent tip-over. Another less ideal transport method would be to have a helper carry or roll a bag or case with the exoskeleton components disassembled or folded. By integrating the exoskeleton and wheelchair, user independence, safety, access, convenience, and energy efficiency are maximized.
A person who uses an exoskeleton and a wheeled base for mobility, or who uses another type of exoskeleton-wheelchair hybrid device, will have significant power consumption requirements to enable exoskeleton standing from a sitting position and exoskeleton walking with bipedal gait. Exoskeletons receive power from energy modules (“EMODs”), with these EMODs being electrical batteries of any type or chemistry, fuel cells, compressed air, or any of a plurality of other energy storage means known in the art. The EMODs used to provide power to exoskeletons have a limited capacity that may be less than the power requirements of a desired exoskeleton use. When more capacity is desired in a single EMOD, the resulting module will typically weigh more. Since the ideal exoskeleton will have no tethers, this EMOD weight will be mounted on the exoskeleton and will therefore be supported and moved by the system. However, mounting heavier EMODs to an exoskeleton will increase power usage. One conventional way to deal with this trade-off is to choose an energy storage method that is as efficient as possible. Another conventional method is to design the exoskeleton power consumption to be as efficient as possible. These are both difficult challenges that are not likely to meet user usage expectations in the near term. In addition, airline and shipping regulations limit the energy capacity in some types of EMODs for safety reasons, providing further restrictions on the portable power supplies that can be used by travelers.
In view of the above, there exists an unmet need in the art to increase the range and operating time of an exoskeleton by increasing the total power available to the exoskeleton. There exists a further unmet need to make this additional power mobile and available to the exoskeleton in locations distal to stationary sources of energy, such as wall outlets. In addition, there exists an unmet need to provide for shared power systems between an exoskeleton and a wheeled base.